The present invention relates to a rotatable grip actuator, or as more commonly known, a twist-grip shifter for shifting of bicycle gear units, such as multi-speed hubs or derailleurs.
EP 0 700 827 discloses a twist-grip shifter for controlling bicycle gear units. This twist-grip shifter includes a shifter housing with a shift mechanism, a clamping device for fixing the shifter on the handlebar, a rotatable take-up spool, a mounting tube on which a twist-grip part is rotatably mounted, and a grip end piece seated non-rotatably on the handlebar. The separate grip end piece is generally an elastomeric tube which is frictionally mounted on the handlebar and primarily transmits the manual supporting forces to the handlebar and, unlike twist-grip shifters without an additional fixed handgrip part, prevents unintentional shifting operations. In order to reduce friction, a plastic intermediate ring can be disposed between the twist-grip part and the fixed elastomeric tube.
In a further development of the twist-grip shifter, EP 1 157 919 discloses a fixed handgrip part or grip end piece of a twist-grip shifter which is formed integrally with the mounting tube. When the mounting tube and shift housing are fixed on the handlebar by means of a screw in a clamping clip, the grip end piece is fixed relative to the handlebar. In this way, unwanted shifting of the grip end piece or even possible slipping off the handlebar is avoided and safety during use is increased. The fixed handgrip part integrally connected to the shifter housing has a corresponding length in the axial direction. This places corresponding demands on the size of injection moulding machines used for the production of the shifter, which is a disadvantage.